<template>
  <div class="pagination">
    <button :disabled='pageNo==1' @click="getpage(pageNo-1)" >上一页</button>
    <button v-if="startAndendNum.start > 1" :class="{active:pageNo===1}" @click="getpage(1)">1</button>
    <button v-if="startAndendNum.start > 2">···</button>

    <!--中间-->
  
      <button v-for="(pages, index) in startAndendNum.end" :key="index"
      v-show="pages >= startAndendNum.start"
      @click="getpage(pages)"
      :class="{active:pageNo===pages}"
      >{{pages}}</button>
   

    <button v-if="startAndendNum.end < totalPage-1">···</button>
    <button v-if="startAndendNum.end < totalPage" @click="getpage(totalPage)"
    :class="{active:pageNo===totalPage}">
    {{ totalPage }}</button>
    <button :disabled='pageNo==totalPage' @click="getpage(pageNo+1)">下一页</button>

    <button style="margin-left: 30px">共{{ total }}条</button>
  </div>
</template>

  
<script>
export default {
   name:'Pagination',
   props:['pageNo','pageSize','total','continues'],
   computed:{
    //算出总共多少页，向上取整
    totalPage(){
      return Math.ceil(this.total/this.pageSize)
      
    },
    //计算出连续页码的起始页和结束页
    startAndendNum(){
      let start=0,end=0
      //1.不正常：连续页码为5，但不足5页
      if(this.totalPage<this.continues){
        start=1,
        end=this.totalPage
      }else{
        //2.总页数大于5页
        start=this.pageNo-parseInt(this.continues/2),
        end=this.pageNo+parseInt(this.continues/2)
        //2.1不正常：start=0/负数
        if(start<1){
          start=1,
          end=this.continues
        }
        //2.2不正常：end大于总页数
        if(end>this.totalPage){
          end=this.totalPage
          start=this.totalPage-this.continues
        }
      }
     return {start,end}
     
   }
},
   methods:{
    getpage(pages){
     this.$emit('getpage',pages)
    }
   }
}
</script>

<style lang="less" scoped>
.pagination {
  text-align: center;
  button {
    margin: 0 5px;
    background-color: #f4f4f5;
    color: #606266;
    outline: none;
    border-radius: 2px;
    padding: 0 4px;
    vertical-align: top;
    display: inline-block;
    font-size: 13px;
    min-width: 35.5px;
    height: 28px;
    line-height: 28px;
    cursor: pointer;
    box-sizing: border-box;
    text-align: center;
    border: 0;

    &[disabled] {
      color: #c0c4cc;
      cursor: not-allowed;
    }

    &.active {
      cursor: not-allowed;
      background-color: #409eff;
      color: #fff;
    }
  }
}
</style>
